Coffee maker



Jan. 3, 1956 A J, HUCK TAL 2,729,159

COFFEE MAKER 2 Sheets-Sheet 1 Jan. 3, 1956 A. .1. HucK ETAL 2,729,159

COFFEE MAKER Filed July l 1950 2 Sheets-Sheet 2 fge/2210219',

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COFFEE MAKER Alred J. Huck and Israel Pass, St. Louis, to Knapp-Monarch Company, St. Louis, ration of Delaware Application July 1, 1950, Serial No. 171,711 4 Claims. (Cl. 99-281) Mo., ussignors Mo., a corpo- This invention relates to a coffee maker or the like of the vacuum type designed to effect a desirable sequence of operations and automatic timing of such operations to result in producing properly brewed coffee each time the coffee maker is used.

One object of the invention is to provide a thermostatic control with a double switching arrangement wherein a main switch operates to initially cut ott the heating element after the water has boiled in the lower bowl and has thereby been displaced into the upper bowl, a secondary control switch being thereafter operable to energize the heating element only sufiiciently to keep the brew at proper drinking temperature.

Another object is to provide a lower bowl construction and particularly the bottom thereof designed in such manner as to conduct heat to the thermostatic switch for causing a desired timing operation thereof in relation to the transfer of water and brew between the upper and lower bowls during the coffee making operation.

Still another object is to provide a bottom construction for t pressed portion which is located beneath the water trans fer tube of the cotee maker.

With these and other objects in view, our invention consists in the construction,

Figure 2 is an enlarged sectional view on the line 2-2 Figure l of Figure l showing a rear elevation of the control switch.

Figure 4 is a bottom plan view of the control switch similar' to Figure 2 showing the parts in a dilerent position for effecting a heating element tie-energizing control function.

are in the position of Figure 4.

Figure 5 is a view similar to Figure 4 showing the parts in still another position.

Figure 5a is a view similar to Figure 4a showing the parts in the position corresponding to Figure 5; and

Figure 6 is a sectional view on the line 6-6 of Figure 3 showing an end elevation of the control switch.

On the accompanying drawings we have used the reference numeral l0 to indicate the lower bowl of a vacuum type coffee maker and 12 thereof. A supporting base in the usual manner on which the lower bowl rests and makers of this type.

The upper bowl 12 includes a transfer tube 14 depending from the bottom thereof and a cover 16 is provided for the upper bowl. A tlter 18 such as shown in the copending application of Alfred J. Huck, Serial No. 144,937, tiled February 18, 1950,

bead 22 for a C-shapcd tubular heating element HE and outside of this or soldering.

The base plate 36 has a heavy leaf spring 44 is adjusting blade 48 is mounted on the leaf spring 44 by hereinafter appear.

The control which has an ear receiving a terminal screw 5l and the A movable carries a Contact i Another movable contact blade 56 is included which for cooperation with thus far described toward or away from a pair of birnetal ele- Patented Jan. 3,v 1956- ments 74 and 78 for temperature adjusting purposes, the heavy spring blade 44 being` biased to retain the adjusting blade 48 in contact with the adjusting screw 68.

The sloping portion 28 of( the bottom of the lower bowl 10 has a raised depression 73 in which a heat conducting bracket 72'1 is soldered. '1T-he bimetal elements 74 and 78V are secured to the heat conducting bracket 72 by bolts 79. The bimetal blade 774 carries ank insulating stud 76 for coasting with the actuating blade 64 at times and the bimetal element 78 carries an adjusting screw Sil providedVv with an insulating point S2 for coaction with the switch blade 60. atcertain temperatures.

The contacts 52 and 58 are normally closed as in Figure. 2 but may be opened b yl the bimetal blade 74 swinging the actuating blade- 64 to the left. as to the position shown in Figure 4, the parts assuming the dotted-,position shown therein at the time thev toggle spring 66 is on dead center and immediately following which the toggle spring throws the actuating blade to the full-line position and the switch blade 5,6'to, its full-line position with the contact 5S separatedY from the contact. 52.

rEhe switch when snappedto this position will not return to the closed position except by a manual resetting operation aCCQmpliShed by a reset rod 84 projecting through a hole 86 in the supporting base 13 of the coffee maker andV normally extended to the position shown in Figure 2 by a Spring 8,8, The spring is on a reduced part of the rod which partrslides through suitable openings in the bar 67 and the ear 71- and is provided with a key 90 inside the ear 71 to limit the outward extension of the reset rod.

The reduced inner end of; thel reset rodV 84 is in alignment with the actuating blade 64l for the purpose of moving it from the position of Figure l-Y back to the position ofY Figure 2 after the bimetal blade 74 has cooled surticientlyA o r entirely and it is desirable to` make another batch of colis-ee.

The bimetal blade. 78v is adapted to coact with the switch blade 60 for opening the contacts 54 and 62 when a predetermined' temperature is exceeded and permits them to reclose when the temperature is lessl lthan the predetermined value.

The connection 61 between the switch blades 5,6 and 6i?, and the contacts 52 and 5.4 both being mounted on the blade 50, elects a connection of the switch contacts Sil- 5S and 541-62 in parallel with each other. Current Supply prongs 22 are provided in the usual way tor connection'of a'service cord thereto, andwires 9 5, 94 and 95 connect the prongs, theA heating element HE and the switch blades together as obvious in Figure 2. Thus whenever the contacts 52 and 58 are open and 54y and 62 are also open, there isno current ilow in theheating element When either or batti. sets Qt @Qatar-ts are Closed, then the heatingy element is energized.

The arrangement diseased rtoyidss a. Y thermostaat Switch t fie-.tiefere the heating @lenient after the Water. has risen from tlie lower bowl to the upper;-V bowl thus controlling the coffee making orvieration by virtue ofvv the fact that the lower bowl thenfco'ols whereupon a vacuum is created therein about three minutes after both the switch contacts are open (they Contacts th-,6,2 brins' opened at a slightly lower'temperature or slightly ahead of the main or snap acting contacts S27-5 8 during.; operation of the coffee maker). 'libe vacuum` created draws the brewed coiee down through the lter 18V into the lower bowl to end the coflee: making operationt The control switchr CS functions as follows: When the water rises intothe). upper bowll leavingcnly the ring of water 26 andthe watery at 32 the lower, bcpivl,I the heating element HEincre Ases bowlz bottom temperature rapidly'whith causer the bimetal fflsiiierits.Y 74 arid.L '78 to rise'sharplyy in ternperaftul?- because of theA heat conducted froml Athe dry slo A ng bottom 2,84, and theY upwardly depressed portion 7,3; thereof; through. the heat, Continuing trinket 72 to the anchored finds'. of? the.

bimetal elements. The bimetal elements at that time are warped to approximately the position show-n in Figure 4 and just prior to the solid-line position the actuating blade 64 is in a dead-center position shown by the dotted lines which as soon as passed-will result in the toggle spring 66 snapping the contact 58 to the solid line position just after the Contact 62 has been separated from the contact 54. This d e-energizes the heating element at about a temperature of 285 F. in the bimetal as compared to about 220 F. therein when the water just rises into the upper bowl. The snap action, of course, opens the contacts 52 and 5S quickly to minimize arcing, and the over-center relationship of thev parts then remains even when the bimetal elements cool asV the toggle spring 66 is so related to the switch blade 5 6 and the actuating blade 64 that it takes a return movement of the blade 64 to close the switch again to its normal position as the insulating stud 76 makes only contact with the blade 6d and is notv connected with it to return it when the bimetal blade 74 cools down.

Since both sets of contactsare now open, no heat is generatedl inl the coiee maker during brew time and this being a critical period, any heat generated during this period would prevent rapid cooling of the lower bowl lil and thus provide excessive brew time and a bittet` brew taste.

Aboutl fifteen minutes after the end of the complete coffee making operation, however, the lower bowl 10 and the bimetal elements 74 and 78 cool sumciently so that the brew (inow in the lower bowl) needs supplementary heat to maintain it atserving temperature. This is accomplished by the bimetal blade 78 and the contacts.y 5.4 and 6,2 which may beV referred to as a keepswarnl switch. These contacts reclose at about 175 Fr. which provides an even heat of about that temperature for the brew in the lower bowl thus keeping it at aproper drinking temperature but at a lower temperature than necessary to cause the brew to again rise tothe upper bowl which would be about2li2 F.

With the disclosed; arrangement, the bimetal blade 74 is4 usedtoactuate a wide dilerential main switch $2- 58; to. control the brewing operation and the bimetal bladey 7,8 is used to control a smallv diilerential temperature limiting switch (contactsl Srl-f and 62) tol keep the brew warrn.

In connection with successful-,operation ot our control, the construction; oi the lower bowl lllv is of considerable importance. We have foundfthat in.l some cases` the temperat-ure of the heat conductor bracket 72 risestoo quicklyl after the water-rises so that; if; the switch 5,2-58 were cut ott when a tolerable increase bimetal temperature occurs, the cut-,out wouldcome so quickly that the brewtime, (or time for the water toY again` drop, to the lower bowl measured starting from the time the water risesv into, the upper bowl) would? be too short for adequate infusion of the. ground coffee by the hot water. We have also found; that. with some constructions, the temperature of the insulating base. 13 and the entire lower bowl temperature become too. high during the interval after the water rises to the upper-bowl.

We have provided a corrective measure for both problerns by contouring: the bottom of the lower bowl so that a predetermined. quantityy Qrring of water 26 remains. after the water rises into the upper bowl- This ring'` of w,a ter serves to delay the temperature rise in the. rsStQfr the, bottom; area; for the` desired interval (usuelly about: que. minute., whit-fh added-i to perhaps two or three minutes required for the water to drop after switch cut-flltv provides an idealthree tov four minutes brew time). 'lfliis ring; of water, also serves: to maintain a cool temperature, iti, the base; 113... and a @00.1 lower bowl temperature. In actual operation with an 800 watt heatina @inseriti the ring, et water; dries ont about. 40 See onds after the water rises into the upper bowl, then permits an ideal l second or 20 second additional interval before the switch cuts off.

The sloping bottom 28 also has an important function in that the area at the heat conductor bracket 72 should definitely be dry immediately after the water` rises. A slanted contour at that point to prevent any pools of water, and a dry upwardly depressed portion 72 near the heating element is required to serve this purpose. The depression 30 at the center is required to hold the small amount of water 32 for a time after the water rises to prevent pumping or the violent up and down movement of the water through the riser tube during the brew time. Such pumping is due to a cornpletely dry bottom and is objectionable because its action is intermittent and during a pump action some water may remain in the lower bowl too long causing premamally short brew time as the remainder of the brew follows it down to the lower bowl.

It is therefore evident that the annular depression 24, the sloping bottom 28, the upwardly depressed portion Some changes may be made in the construction and arrangement of the parts of our coffee maker without departing from the real spirit and purpose of our inequivalents which may be reasonably included within their scope.

We claim as our invention: 1. An automatic coffee maker comprising a bottom bowl, a top bowl on the bottom bowl having a depend making condition to initiate coffee-making operations and means operable to heat the bottom bowl and energized through said switches in parallel.

... A coffee maker comprising in combination, a lower adjustable means interposed between the uniform acting switch and the bimetallic arm means, manual reset means operable to force the snap acting switch to the contact making condition to initiate coiee making operations, and means defining an energizing circuit to the heater through the switches in parallel.

3. An improved lower bowl for a vacuum-type coffee surface sloping upwardly from the periphery of the upper edge of said well side walls, a raised annular portion at the upper and outer peripheral edge of said conical surface, said raised annular portion merging into an annular depressed portion which is positioned outwardly of said raised annular portion and which is depressed below the uppermost level of said raised annular portion, the bottom said bowl within said raised annular portion; and a thermostatic element secured to and responsive to the temperature of said conical portion of the bowl bottom at a point between the annular heater and said central well and being operative to control heating of said heater.

4. An improved lower bowl for a vacuum-type coffee maker, which bowl includes a bowl-defining member havportion of the bowl bottom is free of water thereabove, sucient water to be evaporated by the heater in about 40 seconds.

References Cited in the le of this patent UNITED STATES PATENTS 1,994,323 Peirce Mar. 12, 1935 2,189,127 Brannon Feb. 6, 1940 2,223,450 Jepson et al. Dec. 3, 1940 2,262,286 Ireland Nov. 11, 1941 2,287,583 Weeks June 23, 1942 2,312,555 Jepson Mar. 2, 1943 2,356,784 Graham Aug. 29, 1944 2,365,615 Woodman Dec. 19, 1944 2,367,500 Huck Jan. 16, 1945 2,518,566 Osterheld Aug. 15, 1950 2,522,718 Huck Sept. 19, 1950 2,537,167 Snyder Jan. 9, 1951 2,552,420 Frankel May 8, 1951 2,577,985 Willman Dec. 11, 1951 2,690,709 Farr et al. Oct. 5, 1954 

